A mobile station may communicate with a first radio network, such as a wireless local area network (“WLAN”) that uses one of the various Institute of Electrical and Electronics Engineers (“IEEE”) 802.11 protocols. The mobile station may communicate with other devices on the first radio network. The first radio network may additionally provide connectivity to one or more other networks, such as packet data networks, thereby allowing the mobile station to also communicate with devices on those other networks.
In addition to the first radio network, the mobile station may also communicate with a second radio network, such as a wireless wide area network (“WWAN”). The mobile station may connect to the second radio network and then communicate with other devices on the second radio network. The second radio network may additionally provide connectivity to other networks, such as packet data networks. The mobile station may then also communicate with devices on those other networks.
The mobile station may communicate with one or both of the radio networks, which can provide the mobile station with voice, data or other services. Although both radio networks may provide the mobile station with one or more of these services, one radio network may provide the mobile station with higher data speeds or lower access charges that make communicating with that network preferable. Therefore, even when the mobile station is communicating with one of the radio networks, it might still be preferable for the mobile station to determine the availability of the other radio network and then switch to communicating with that radio network.
Further, the first and second radio networks may have different coverage areas, thereby potentially creating areas where the mobile station might only be able to access one of the radio networks. For example, as the mobile station changes location, it may leave the coverage area of one of the radio networks and then only be in the coverage area of the other radio network. If the mobile station were not already communicating with the other radio network, it might be advantageous for the mobile station to detect that radio network's availability and to begin communicating with that radio network.
Current methods for detecting the availability of a radio network have various limitations. In one method of detecting the availability of a radio network, a user of the mobile station manually prompts the mobile station to check the availability of the radio network, such as in response to a command from the user. This can disadvantageously create a delay in detecting the availability of the radio network, because while the mobile station may be within range of the radio network, the mobile station would only detect the radio network if it receives the command from the user. A delay in making the request would cause a delay in detecting the radio network's availability, and if the user did not even make a request, then the mobile station would not ever detect the radio network's availability and may lose existing radio network connectivity.
In another method of detecting the availability of the radio network, the mobile station might automatically check for the radio network's availability at predetermined time intervals. The mobile station might communicate with the radio network using a radio or other transceiver, which the mobile station can power-up and then use to check the radio network's availability. If the radio network is not available, then the mobile station might power-down the radio until the next predetermined interval when it again check the radio network's availability. Powering-up and powering-down the radio in this manner consumes battery power, which can be undesirable for battery-powered mobile stations. Similarly, continually leaving the radio on rather than periodically turning it on and off also consumes battery power and therefore may be undesirable.
Therefore, there exists a need for other methods for triggering a mobile station to perform predetermined actions, such as checking the availability of a radio network.